Location pad for neurosurgical procedures

ABSTRACT

A location pad includes multiple field-generators and a frame. The multiple field-generators are configured to generate respective magnetic fields in a region-of-interest of a patient organ, so as to measure a position of a medical instrument in the region-of-interest. The frame is transparent to an X-ray radiation, and is configured to fix the multiple field-generators at respective positions surrounding the region-of-interest.

FIELD OF THE INVENTION

The present invention relates generally to medical devices, andspecifically to location pads of magnetic position tracking systems usedin neurosurgical procedures.

BACKGROUND OF THE INVENTION

Magnetic position tracking systems are used in a wide range of medicalapplications, such as in minimally invasive procedures. Examples ofprior art techniques are provided below.

U.S. Patent application publication 2017/0007155 describes a locationpad of a magnetic position tracking system. The location pad includesmultiple field-generators and a frame. The field-generators areconfigured to generate respective magnetic fields in aregion-of-interest of a patient body, for measuring a position of amedical instrument in the region-of-interest. The frame is configured tofix the multiple field-generators at respective positions surroundingthe region-of-interest. The frame is open on at least one side of theregion-of-interest.

U.S. Patent application publication 2014/0275998 describes a system fornavigating a medical device including a magnetic field generatorassembly that generates a magnetic field. Position sensors on themedical device, on an imaging system and on the body generate signalsindicative of the positions within the magnetic field. The generatorassembly and reference sensors are arranged such that a correlationexists between them and the positions of the body and of a radiationemitter and a radiation detector of the imaging system. An electroniccontrol unit (ECU) determines, responsive to signals generated by thesensors, a position of the medical device, a position of one of theradiation emitter and detector and a distance between the emitter anddetector.

SUMMARY OF THE INVENTION

An embodiment of the present invention that is described herein providesa location pad including multiple field-generators and a frame. Themultiple field-generators are configured to generate respective magneticfields in a region-of-interest of a patient organ, so as to measure aposition of a medical instrument in the region-of-interest. The frame istransparent to an X-ray radiation, and is configured to fix the multiplefield-generators at respective positions surrounding theregion-of-interest.

In some embodiments, the field-generators include at least first andsecond field-generators, and the location pad includes at least a firstelectrical cable connected to the first field-generator, and a secondelectrical cable connected to the second field-generator, and the firstand second electrical cables are positioned out of theregion-of-interest. In other embodiments, the frame includes a substanceselected from a list of substances consisting of carbon and organicpolymer. In yet other embodiments, the patient is positioned on a table,and the location pad is configured to be positioned between the patientand the table.

In an embodiment, at least one of the field-generators includes multiplenon-concentric coils. In another embodiment, at least one of thefield-generators includes multiple concentric coils.

There is additionally provided, in accordance with an embodiment of thepresent invention, a method for producing a location pad, the methodincludes providing multiple field-generators for generating respectivemagnetic fields in a region-of-interest of a patient organ, so as tomeasure a position of a medical instrument in the region-of-interest.The multiple field-generators are fixed on a frame at respectivepositions surrounding the region-of-interest, and the frame istransparent to X-ray radiation, at least at the region-of-interest.

There is further provided, in accordance with an embodiment of thepresent invention, a method including positioning a location padrelative to a region-of-interest of a patient, the location pad includesa frame that fixes multiple field-generators at respective positionssurrounding the region-of-interest, and the frame is transparent to anX-ray radiation at least at the region-of-interest. A medical instrumentis inserted into the region of interest. A position of the medicalinstrument is tracked using the field-generators. Simultaneously withthe position tracking, the region-of-interest is irradiated with afluoroscopic imaging system, so as to produce an image of theregion-of-interest.

The present disclosure will be more fully understood from the followingdetailed description of the embodiments thereof, taken together with thedrawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic pictorial illustration of a neurosurgical system,in accordance with an embodiment of the present invention;

FIG. 2 is a schematic top-view of a fluoro-transparent location pad, inaccordance with an embodiment of the present invention; and

FIG. 3 is a flow chart that schematically illustrates a method forsimultaneous imaging and position tracking during a neurosurgicalprocedure, in accordance with embodiments of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS Overview

Medical instruments and guidewires are used in various therapeutic anddiagnostic medical procedures, such as in neurosurgery.

Embodiments of the present invention that are described hereinbelowprovide methods and apparatus for improving anatomical imaging andsimultaneously tracking medical instruments during neurosurgicalprocedures.

In neurosurgical procedures carried out using a neurosurgical system, asurgeon may insert a guidewire into the patient head and may navigatethe guidewire to the target region in the patient brain for performingthe neurosurgical procedure.

In some embodiments, the neurosurgical system may comprise a magneticposition tracking subsystem, which is configured to track the positionof the guidewire in the patient head. In some embodiments, the magneticposition tracking subsystem comprises multiple field-generators that aretypically fixed on a location pad, and are configured to applyrespective magnetic fields to a region-of-interest (ROI) at the patienthead. In some embodiments, the magnetic position tracking subsystemcomprises a position sensor, typically installed at the distal end ofthe guidewire. The position sensor is configured to produce, in responseto the magnetic fields, a position signal indicative of the position andorientation of the distal end within the patient head.

In some embodiments, the position tracking subsystem comprises aprocessor, which is configured to display, based on the position signal,a position of the distal end overlaid on an anatomical image of thepatient head.

In some scenarios, it is desirable to apply a fluoroscopic systemsimultaneously with the magnetic position tracking system. For example,in order to acquire an X-ray image, also referred to herein as afluoroscopic image, of the ROI of the patient head or of any other organin question. In a neurosurgical procedure, parts of the location pad mayfall within the irradiated volume of the fluoroscopic system, and mayblock or obstruct portions of the fluoroscopic image of the patientbrain.

In some embodiments, the location pad comprises a frame that istransparent to the X-ray radiation, also referred to herein as“fluoro-transparent,” at least at the ROI. The fluoro-transparent frameis configured to fix the field-generators thereon, at respectivepositions surrounding the ROI. The transparency of the frame to theX-ray radiation causes little or no obstruction to the fluoroscopicimaging, at least in fluoroscopic projections that are commonly used inneurosurgical procedures.

In some embodiments, the location pad may comprise field-generatorshaving non-concentric coils arranged so as to enable a low profilelocation pad. Such a location pad can be easily placed between a movingtable, on which the patient is positioned, and the patient head, asopposed to conventional location pads that are thicker and have to beplaced below the table. In other embodiments, at least one of (andtypically all) the field-generators may comprise concentric coils. Thisconfiguration may be used in case the low profile location pad is notnecessary, or for enhancing the functionality of the location pad.

The disclosed techniques improve the quality of neurosurgical proceduresby enabling simultaneous imaging and treatment of the brain duringsurgical or any other invasive procedures. Moreover, the disclosedtechniques may be applied, mutatis mutandis, to medical procedurescarried out on other organs of the patient body.

System Description

FIG. 1 is a schematic pictorial illustration of a neurosurgical system10, in accordance with an embodiment of the present invention. In someembodiment, neurosurgical system 10 comprises a fluoroscopic imagingsubsystem 22, which is configured to irradiate X-rays to an organ inquestion, and a magnetic position tracking subsystem 20 described indetail below.

Reference is now made to an inset 32. In some embodiments, during aneurosurgical procedure, a surgeon 42 navigates any suitable type of aguidewire 24, into a brain 28 of a patient 30. In some embodiments, aposition sensor 41 is coupled to a distal end 34 of guidewire 24.

In some embodiments, surgeon 42 navigates distal end 34 to a targetlocation within a region-of-interest (ROI) 39 of brain 28, andsubsequently, applies a medical device (not shown) typically guidedalong guidewire 24 to distal end 34, so as to carry out a medicalprocedure in ROI 39, e.g., tumor removal.

Reference is now made to an inset 27. In some embodiments, neurosurgicalsystem 10 comprises a low-profile location pad 38 placed below the headof patient 30. Location pad 38 comprises field-generating coils,referred to herein as field-generators 36A-36D that are mounted on aframe 37 around ROI 39.

In some embodiments, frame 37 is transparent to X-rays, such that X-raysirradiated by an X-ray source 23 of subsystem 22, pass through pad 38and brain 28, and sensed by an X-ray detector 25. Note that frame 37 hasa low-profile (e.g., thickness of about 1.2 cm) and X-ray detector 25 isconfigured to output electrical signal indicative of the sensed X-raysfor producing an anatomical image 35 of at least a section of ROI 39, aswill described below.

In some embodiments, location pad 38 further comprises electrical cables60 and 62 configured to electrically couple between field-generators36A-36D and a driver circuit 50 of magnetic position tracking subsystem20. Location pad 38 is described in more detail in FIG. 2 below.

In the context of the present disclosure, the terms “about” or“approximately” for any numerical values or ranges indicate a suitabledimensional tolerance that allows the part or collection of componentsto function for its intended purpose as described herein. Morespecifically, “about” or “approximately” may refer to the range ofvalues ±20% of the recited value, e.g. “about 90%” may refer to therange of values from 71% to 99%.

In some embodiments, neurosurgical system 10 comprises an operatingconsole, referred to herein as a console 26 for brevity. Console 26comprises a processor 44, driver circuit 50, interface circuitry 48 tofluoroscopic imaging subsystem 22, input devices 46, and a display 40.In the exemplary configuration of FIG. 1 , pad 38 comprises fourfield-generators 36A-36D, in other embodiments, pad 38 may comprise anyother suitable number of field-generating coils.

In some embodiments, position sensor 41 is configured to sense magneticfields generated by field-generators 36A-36D and to transmit, toprocessor 44, electrical signals indicative of the position andorientation of distal end 34 in ROI 39.

Magnetic position tracking subsystem 20 may be implemented, for example,in the CARTO™ system, produced by Biosense Webster Inc. (Irvine, Calif.)and is described in detail, for example, in U.S. Pat. Nos. 5,391,199,6,690,963, 6,484,118, 6,239,724, 6,618,612 and 6,332,089, in PCT PatentPublication WO 96/05768, and in U.S. Patent Application Publications2002/0065455 A1, 2003/0120150 A1 and 2004/0068178 A1, whose disclosuresare all incorporated herein by reference.

Reference is now made to an inset 29. In some embodiments, location padis positioned on top of a table 33 and under the patient head, such thatgenerators 36A-36D are located at fixed, known positions external topatient 30. Driver circuit 50 is configured to drive field-generators36A-36D with suitable signals so as to generate the aforementionedmagnetic fields in a predefined volume around ROI 39 of brain 28.

In some embodiments, at least one of field-generators 36A-36D maycomprise three non-concentric coils arranged and packaged in a lowprofile field-generator. Each coil is thus configured to generate amagnetic field component in one direction out of threemutually-orthogonal directions. In this configuration two of the coilsare positioned side-by-side in a given plane, and the third coil iswound around the two coils in the given plane so as to obtain the lowprofile field-generator. This configuration is described in detail inU.S. Patent application publication 2017/0007155, whose disclosure isincorporated herein by reference.

In other embodiments, at least one of field-generators 36A-36D maycomprise three concentric coils. Such configuration, however, typicallyresults in a thicker field-generator. Note that typically allfield-generators 36A-36D have the same configuration, and thearrangement of the coils is determined based on various parameters, suchas but not limited to the specified thickness of the location pad. Inthe example of neurosurgery the thickness may not be critical, andtherefore both configurations may be applicable. Note that location pad38 may comprise any suitable number of field-generators, other thanfour.

In some embodiments, an operator of neurosurgical system 10 may produceanatomical image 35 by operating subsystem 22 using input devices 46 anda suitable graphical user interface (GUI), and processor 44 isconfigured to display anatomical image 35 on display 40. In someembodiments, processor 44 is further configured to receive, fromposition sensor 41, a position signal indicative of the position ofdistal end 34 in brain 28. Based on the position signal, processor 44 isconfigured to display (a) the position of distal end overlaid onanatomical image 35, and (b) a frame, indicative of the position of ROI39, so that an operator of subsystem 22 may adjust the direction of theirradiated X-rays on the head of patient 30.

This particular configuration of neurosurgical system 10 is shown by wayof example, in order to illustrate certain problems that are addressedby embodiments of the present invention and to demonstrate theapplication of these embodiments in enhancing the performance of such asystem. Embodiments of the present invention, however, are by no meanslimited to this specific sort of example system, and the principlesdescribed herein may similarly be applied to other sorts of surgicalsystems, and particularly, to other sorts of position tracking systemsapplied in conjunction with imaging systems or subsystems, such as butnot limited to, fluoroscopic-based, or computerized tomography(CT)-based systems or subsystems.

Location Pad Transparent to X-Ray Radiation

FIG. 2 is a schematic top-view of location pad 38, in accordance with anembodiment of the present invention. In some embodiments, frame 37comprises a rigid substance that is transparent to X-rays, such as butnot limited to carbon film, carbon fiber and various types of organicpolymers (e.g., plastic).

In some embodiments, field-generators 36A and 36D are fixed at one sideof frame 37 using a fixing device 66, and are electrically connected todriver circuit 50 via electrical cable 62. Similarly, field-generators36B and 36C are fixed at the opposite side of frame 37 using a fixingdevice 64, and are electrically connected to driver circuit 50 viaelectrical cable 60. In such embodiments, field-generators 36A-36D,fixing devices 64 and 66, and electrical cables 60 and 62, are all fixedon frame 37 outside ROI 39, as shown in FIG. 2 .

In some embodiments, fixing devices may be movable to other locations onthe surface of frame 37, so as to set the size and shape of ROI 39.

In other embodiments, frame 37 is configured to fix field-generators36A-36D at respective positions surrounding ROI 39. In such embodiments,field-generators 36A-36 may be attached on frame 37 using any suitabletechnique, such as but not limited to gluing, welding, soldering, orscrewing. Note that in this configuration, fixing devices 64 and 66 maybe removed from location pad 38.

In some embodiments, field-generators 36A-36D are configured to generaterespective magnetic fields in ROI 39 of patient brain 28 so as tomeasure the position of distal end 34 in ROI 39. In such embodiments,when surgeon 42 is positioning distal end 34 at a position 70 withinbrain 28, processor 44 is receiving from position sensor 41 a positionsignal indicative of position 70, and overlays position 70 on anatomicalimage 35.

In some embodiments, surgeon 42 may use guidewire 24 for positioning anysuitable medical instrument for performing the medical procedure.Additionally or alternatively,

In other embodiments, surgeon 42 may use the same techniques forpositioning, at a target position within brain 28, any otherneurosurgical-related medical device having position sensor 41 coupledto its distal end. In such embodiments, guidewire 24 may be removed fromthe configuration of neurosurgical system 10.

Simultaneous Imaging and Position Tracking During A NeurosurgicalProcedure

FIG. 3 is a flow chart that schematically illustrates a method forsimultaneous imaging and position tracking during a neurosurgicalprocedure, in accordance with embodiments of the present invention.

The method begins at a patient positioning step 100, with positioningpatient 30 on table 33, relative to location pad 38, such that locationpad 38 is positioned between table 33 and the patient head. At aguidewire insertion step 102, surgeon 42 inserts guidewire 24 into thehead of patient 30.

At a tracking step 104, which is carried out during the neurosurgicalprocedure, surgeon 42 may apply magnetic position tracking subsystem 20for tracking distal end 34. In such embodiments, surgeon 42 may useconsole 26 for controlling driver circuit 50 to apply the aforementionedmagnetic fields to ROI 39, and further controls position sensor 41 andprocessor 44 for tracking the position of distal end 34 in brain 28 andfor displaying the position overlaid on anatomical image 35. At anirradiation step 106, which is carried out in parallel to tracking step104, surgeon 42 may apply subsystem 22 for irradiating ROI 39 of brain28. Note that the structure of location pad 38 enables simultaneousimaging of ROI 39 and position tracking of distal end 34 within ROI 39.

At a medical procedure conducting step 108, surgeon 42 conducts theneurosurgical procedure based the displayed position of distal end 34overlaid on anatomical image 35. Note that step 108 typically terminatesthe method of FIG. 3 , however, surgeon may apply steps 104 and 106simultaneously to carry out additional activities related to theprocedure, such as but not limited to retracting distal end 34 out ofthe head of patient 30.

Although the embodiments described herein mainly address neurosurgicalprocedures, the methods and systems described herein can also be used inother applications.

It will thus be appreciated that the embodiments described above arecited by way of example, and that the present invention is not limitedto what has been particularly shown and described hereinabove. Rather,the scope of the present invention includes both combinations andsub-combinations of the various features described hereinabove, as wellas variations and modifications thereof which would occur to personsskilled in the art upon reading the foregoing description and which arenot disclosed in the prior art. Documents incorporated by reference inthe present patent application are to be considered an integral part ofthe application except that to the extent any terms are defined in theseincorporated documents in a manner that conflicts with the definitionsmade explicitly or implicitly in the present specification, only thedefinitions in the present specification should be considered.

1-16. (canceled)
 17. A location pad, comprising: (a) multiplefield-generators, which are configured to generate respective magneticfields in a region-of-interest of a patient organ, for measuring aposition of a medical instrument in the region-of-interest; (b) a frame,which is configured to fix the multiple field-generators at respectivepositions surrounding the region-of-interest; and (c) a fixing assemblyassociated with both the multiple field-generators and the frame,wherein the fixing assembly is configured to allow the multiplefield-generators to move to multiple locations of a surface of the framein order to adjust the size and shape of the region-of-interest.
 18. Thelocation pad according to claim 17, wherein the field-generatorscomprise at least first and second field-generators, and comprising atleast a first electrical cable connected to the first field-generator,and a second electrical cable connected to the second field-generator,and wherein the first and second electrical cables are positioned out ofthe region-of-interest.
 19. The location pad according to claim 17,wherein the frame comprises a substance selected from a list ofsubstances consisting of carbon and organic polymer.
 20. The locationpad according to claim 17, wherein the patient is positioned on a table,and wherein the location pad is configured to be positioned between thepatient and the table.
 21. The location pad according to claim 17,wherein at least one of the field-generators comprises multiplenon-concentric coils.
 22. The location pad according to claim 17,wherein at least one of the field-generators comprises multipleconcentric coils.
 23. A method for producing a location pad, the methodcomprising: (a) providing multiple field-generators for generatingrespective magnetic fields in a region-of-interest of a patient organ,so as to measure a position of a medical instrument in theregion-of-interest; (b) utilizing a fixing assembly to adjust thespatial positioning of the multiple field-generators in order to set thesize and shape of the region-of-interest; and (c) fixing the multiplefield-generators on a frame at respective positions surrounding theregion-of-interest.
 24. The method according to claim 23, wherein thefield-generators comprise at least first and second field-generators,and comprising connecting a first electrical cable to the firstfield-generator, and a second electrical cable to the secondfield-generator, and positioning the first and second electrical cablesout of the region-of-interest.
 25. The method according to claim 23,wherein at least one of the field-generators comprises multiplenon-concentric coils.
 26. The method according to claim 25, andcomprising arranging at least two of the non-concentric coilsside-by-side in a given plane.
 27. The method according to claim 23,wherein at least one of the field-generators comprises multipleconcentric coils.
 28. The method according to claim 23, wherein theframe comprises a substance selected from a list of substancesconsisting of carbon and organic polymer.
 29. A method, comprising: (a)positioning a location pad relative to a region-of-interest of apatient, wherein the location pad comprises a frame that fixes multiplefield-generators at respective positions surrounding theregion-of-interest; (b) adjusting the spatial position of the multiplefiled-generators utilizing a fixing device of the frame in order to setthe size and shape of the region-of-interest; (c) inserting a medicalinstrument into the region of interest; (d) tracking a position of themedical instrument using the field-generators; and (e) simultaneouslywith tracking the position, irradiating the region-of-interest with afluoroscopic imaging system so as to produce an image of theregion-of-interest.
 30. The method according to claim 29, whereinpositioning the location pad comprises placing the location pad betweenthe patient and a table on which the patient is positioned.
 31. Themethod according to claim 29, wherein tracking the position comprisesproducing magnetic fields using the field-generators, and tracking theposition by applying magnetic position tracking to the produced magneticfields.
 32. The method according to claim 29, wherein theregion-of-interest comprises at least a volume of a brain of thepatient, and wherein inserting the medical instrument comprisesinserting a guidewire for performing a neurosurgical procedure at theregion of interest.
 33. The method according to claim 29, wherein thelocation pad comprises a low profile.
 34. The method of claim 29,wherein the multiple field-generators comprises concentric coils. 35.The method of claim 29, wherein the medical instrument comprises aguidewire
 36. The method of claim 29, wherein the medical instrumentcomprises a position tracking sensor.